Among Rohit Shekhar's earliest childhood memories are visits from a kindly "uncle" who would come to his mother's Delhi home, bringing him snazzy pencil boxes and chocolates, and sing Hindi movie songs to him.

As he grew older, he heard him shouting with his mother behind closed doors, the tone increasingly acrimonious over time. Those visits tapered off after Shekhar turned 16 and eventually stopped altogether.

But over the past five years, they have been seeing each other again - in court. Shekhar was in a legal battle to force that "uncle", prominent Indian politician Narayan Dutt Tiwari, to take a DNA test to prove a familial tie. He emerged victorious in July, when the Indian Supreme Court pronounced Tiwari to be his biological father.

Borrowing a line from a Bollywood hit, Shekhar, 33, said after the ruling: "I am not his illegitimate son. He is my illegitimate father."

Indians have been riveted by the twists and turns of Shekhar's legal challenge, which is unprecedented on many fronts. Not only is it a bid to seek recognition for children born out of wedlock, it also involves a rare public admission by a married woman to having had an affair and a child from her lover.

Many powerful businessmen and politicians are known to enjoy long-standing extramarital affairs, but this is never acknowledged and the Indian media refrains from any exposés. Typically, the women are from a lower social strata and when the relationship flags, they can be ditched without worry because the women would never admit to the affair or having a child from the union for fear of drawing shame.

Shekhar's mother, Ujjwala Sharma, however, was different. Confident and highly educated, she is a member of a distinguished political family and a Sanskrit scholar who used to teach at Delhi University.

Perhaps for these reasons, no one in this family drama stuck to their customary roles in Indian society. Sharma would not to keep her relationship with Tiwari under wraps, and Shekhar refused to lick his wounds in private and forget his humiliation as an unwanted and unacknowledged child. Even the courts ventured into new territory by ordering, for the first time, a DNA test in a civil case.

The story began in the mid-70s when Ujjwala was in her mid-20s. She had separated from her husband, Bipin Sharma, and Tiwari, then an up-and-coming politician, began courting her after they met at her father's home in Delhi.

"When she was 30 and he was 50, he asked her to bear him a child as his wife was barren. He promised to marry her later and be a father to their child," Shekhar says.

Tiwari repeated this pledge over the years but constantly put off any action, arguing that the scandal would hurt his political career (at one time, he was considered a potential prime minister).

Gradually, Ujjwala realised her hopes of marriage and recognition for their son were futile. Tiwari failed to act even after his wife died in 1993; instead, their contact faded during Shekhar's adolescence, by which time he had been told the truth about his father. Then Tiwari severed ties with them entirely.

The repudiation plunged Shekhar into anger and confusion.

In a deeply conservative country like India, where marriage and family are vital for social respectability, the stigma of being "illegitimate" is profound.

"I went through hell in those years, unable to sleep or concentrate. I felt humiliated and angry. The idea of this man not accepting me was terrible. By the time I went to college to study law, I was suffering from insomnia and depression," he says.

Such reactions are only natural, says Delhi-based psychiatrist Dr Samir Parikh: "While a child's response to this situation varies depending on the age and level of support that's available, any form of parental rejection is a wound."

Baby-faced but intense, Shekhar talks about his experience at length, as though it will unburden him. The hurt he felt at his father's rejection, he says, triggered a stroke and a heart attack when he was 28. Even now, a slight breathlessness is evident when he becomes emotional.

The battle to be recognised by his father has consumed much of Shekhar's life so far. He has memorised every legal ruling related to his case, its date, intent and other minutiae, and his bedroom is filled with documents and newspaper clippings.

"Lots of people told me not to bother when I decided to take him to court to prove he was my father. They said I was wasting my time, that he would punish me, destroy me," he says.

But Shekhar was determined to teach his father a lesson, and filed a petition in the courts in 2007 to seek a DNA test. The ruling in Shekhar's favour has set a new legal precedent. Framed in the days before DNA tests, Section 112 of the Indian Evidence Act states that a child born during a marriage is "presumed" to be the offspring of the married couple. So, according to this law, Shekhar is deemed to be Bipin Sharma's son even though he is not. The archaic clause was drafted in 1872, in the days of the British Raj, to prevent husbands from denying paternity of their child but is inappropriate for these times, says Mumbai-based legal expert Flavia Agnes.

Because of the presumption, however, a married woman who has a child with another man has no legal recourse if she seeks maintenance.

"I have lots of such cases," Agnes says. "Married women may have a child with another man for all sorts of reasons - they are separated but not divorced, or the husband is impotent or an invalid. If she and her child are later discarded by her lover, she is not allowed to prove that he is the father. It leaves her helpless. The lover knows the law can't touch him because it presumes that the husband is the father."

The new ruling, she says, will help tens of thousands of women because they can now ask for a DNA test to prove paternity.

Shekhar adds: "Indian society is still feudal. Powerful men take advantage of women who are vulnerable and can't take them on if they are abandoned or humiliated. My case sends out a message to all these men that this is no longer possible."

A practising lawyer himself, he is frustrated by how the law has been so slow to move with the times.

"We have surrogate mothers, gay marriages, test-tube babies, live-in relationships, children born out of wedlock, and all permutations of sexual relationships. Yet our laws still talk of 'concubines' and 'keeps' and 'bastards'. These terms are hateful and outdated," he says.

Having lived with the sting all his life, Shekhar now plans to campaign against the use of such words in Indian law. He is appalled at the continued discrimination against children born out of wedlock. Countries around the world, including India, have moved to stop discrimination - against homosexuals, minorities and the handicapped - and ban the use of pejorative terms to describe such groups.

"But we allow innocent children to be called insulting names. During the case, I was routinely called a bastard. How can such ugly abusive words be used in courts? Why should a child be stigmatised when he's done nothing wrong," he asks.

For Shekhar himself, the psychological damage of being rejected by his biological father may well take a lifetime to heal.

"It is inhuman not to acknowledge your own child," he says. "He has been ruthless, inhuman. For the past 33 years, he has violated my human right to be a normal child."